Rolling mill and coiling apparatus



Sept. 29, 1953 H. F. ANDERSON 2,653,496

ROLLING MILL AND COILING APPARATUS Filed Nov. 25, 1947 2 Sheets-Sheet 1 FIG. I

ATTORNEYS Sept. 29, 1953 H. F. ANDERSON ROLLING MILL AND COILING APPARATUS 2 Sheets-Sheet 2 Filed Nov. 25, 1947 E IIINIII w INVENTOR haward A rfrrm' ru-arl ATTORNEYS Patented Sept. 29, 1953 ROLLING MILL AND COILING APPARATUS Howard F. Anderson, Torrington, Conn., assignor to The American Brass Company, a corporation of Connecticut Application November 25, 1947, Serial No. 788,057

6 Claims. 1

This invention relates to rolling sheet metal, and is particularly concerned with the provision of improved automatic apparatus for use in conjunction with rolling mills equipped with apparatus for coiling the sheet metal as it emerges from the rolls. The principal object of the invention is to provide apparatus for automatically performing the operation known in the industry as pulling a tail on the coil into whichthe sheet metal is wound. The so-called tail of the coil is a flat uncoiled length at the trailing end of the sheet metal-the last part thereof to emerge from between the rolls. This uncoiled end, or tail, at the outside of the coil, is necessary in order to present the coil to a subsequent rolling or other operation. If no tail is formed, i. e. if the whole length of the metal sheet (or bar, as it is customarily called) is coiled, then the coil must be opened by hand or otherwise in order to present it to the next subsequent operation, and this is often a diflicult thing to do, especially with fairly heavy gauge sheet metal.

It has heretofore been customary to pull or form the tail on sheet metal coils being wound on the exit side of a rolling mill by hand manipulation of the coiling apparatus controls. Tail pulling in this fashion requires a very alert operator, because it requires manipulation of the con trols at exactly the right time in the very short interval of time following emergence of the trailing end of the sheet metal, or bar, from between the rolls of the rolling mill, and just before it enters the coiling apparatus, in order to discontinue the ceiling operation at the proper instant and to leave a flat uncoiled tail of proper length. Even the most experienced operators find it difficult to pull tails of uniform length, that are neither too long to interfere with easy handling of the coil, nor too short for easy presthe mill, as it emerges therefrom, is equipped with electric control apparatus for automatically discontinuing the coiling action of the coiling apparatus at the precise moment for leaving a tail of desired length for the next subsequent operation such as further rolling, slitting, trimming, etc. The electrical control apparatus comprises first switch means connected with the rolling mill and caused to close promptly upon emergence of the trailing end of the sheet metal from between the rolls. A timer is connected to the first switch means so as to become actuated by closure thereof. A control circuit including second switch means is also connected to the timer, so that said second switch means are closed promptly at the end of the predetermined timing interval for which the timer is set. This control circuit and its second switch means is connected to the coiling apparatus and serves, upon closure of the second switch means, to discontinue the coiling action thereof. Thereby a tail of length determined by the speed of travel of the sheet metal through the rolls, and by the length of the timing interval of the timer, is produced automatically on the coil of metal formed by the coiling apparatus.

It is common practice to eject the coil from the coiling apparatus onto a conveyor, for carrying it to the next subsequent rolling or other operation. Frequently the coiling apparatus ejects the coil with the tail at the bottom, and it is desirable to turn the coil over, to bring the tail to the top, for convenience in presenting the coil to a subsequent operation. The invention contemplates the provision of apparatus for effecting this change in position automatically, directly after ejection of the coil from the coiling apparatus. In accordance with this feature of the invention, a coil positioner is included in the conveyor, and a second electrical control apparatus, which may be identical with that for controlling automatic formation of the tail, is employed for actuating the coil positioner at a predetermined time interval following ejection of the coil from the coiling apparatus.

A preferred embodiment of the invention, in which the foregoing and other features are incorporated, is described below in conjunction with the accompanying drawings. Also described are alternative arrangements of various indi- 3 vidual components of the new apparatus. the drawings,

Fig. 1 shows, more or less schematically, a rolling mill and associated coiling apparatus embodying the invention;

Fig. 2 shows, schematically, a form of control circuit in accordance with the invention; and

Fig. 3 shows, schematically, apparatus for changing the position of the coil following its ejection with a tail from the coiling apparatus.

The apparatus shown in Fig. 1 comprises a rolling mill ill, and coiling apparatus II for coiling the so-called bar, or sheet, emerging from the rolling mill. The rolling mill and coiling apparatus are both of conventional construction. The rolling mill comprises a heavy frame I2 which provides support for the rolls 13. The rolls are driven through a suitable reducing gear train [4, by an electric motor l5. Sheet metal l6 emerging from the rolls 13 passes between guide plates H to top and bottom power driven coiling rolls l8 and 19 of the coiling apparatus. These rolls impart a curvature to the sheet metal, so that it loops upwardly and winds into a compact coil 20. V

The upper coiling roll I 8 is mounted at each end on a vertically movable supporting member 21. With these members held in their lowermost position, the roll 18 cooperates with the fixed lower rolls 19 to impart a set curvature in the sheet metal and cause it to wind into a coil. By releasing the members 2!, causing them to move to theirupper position and lift the upper roll it away from the lower rolls 19, the coiling action of the apparatus is discontinued.

The release of the members 24 and ejection of the coil from the coiling apparatus is accom-- plished by a kick-off mechanism comprising a kick-off shoe 22 which normally is in the position shown in full lines in Fig. 1. In this position it forms a backstop for the coiling sheet metal and serves to guide the coil as it is being formed. The kick-01f shoe 22 is secured to and supported on a pivot shaft 23, to which the midpoint of a lever 24 is also attached. One end of the lever 22 is pivotally connected by a link 25 to a piston rod 26 connected to a piston within a compressed air cylinder 2'1. A pair of air pipes 28 and 29 provide, respectively, for admitting compressed air above and below the piston within the cylinder 21. The other end of the lever 25 is pivotally connected to one end of a connecting rod 31!, the other end of which is pivotally connected to a bell crank lever 3| mounted on a shaft 32. The bell crank 3! also is linked to a push rod 33 which actuates the vertically movable supporting members 21 for the upper coiling roll E8.

The kick-off shoe 2-2 is maintained in the position shown in solid lines in Fig. 1 when compressed air is admitted through the lower air pipe 29 to beneath the piston in the cylinder 27 and the upper pipe-28 is opened to the atmosphere. In this position also the bell crank lever 3| is in the position shown, holding the upper coiling roll it in its lowered position to cooperate with the fixed coiling rolls [9 and exert a coiling action on the sheet metal or bar coming from the rolls. When, however, compressed air is admitted through the upper air pipe 28 above the piston in the cylinder 27 (the lower air pipe 29 then being opened to the atmosphere), the piston is forced down, moving the kick-off shoe 22 approximately to the position indicated by the dotted lines in Fig. 1. At the same time, the

4 bell crank lever is rotated (in a clockwise direction) by the lever 24 and the connecting rod 30, raising the push rod 33 and releasing the supporting member 2! so that the upper coiling roll is raised sufficiently to discontinue further coiling action on the bar of sheet metal passing beneath it. The forward motion of the kick-01f shoe 22 from the position shown in solid lines to that shown in dotted lines ejects the coil of sheet metal from the coiling apparatus onto a conveyor 34 (indicated only schematically in Fig. 1). Thereafter, by reconnecting the lower air pipe 29 to a source of compressed air, and the upper pipe 26 to an exhaust to the atmosphere, the piston within the cylinder 21 is returned to the upper limit of its travel, the kick-cit shoe 22 is returned to the position shown in full lines, and the upper coil roll [8 is again brought down into position to exert a coiling action on the next bar passed through the rolling mill.

The supply of compressed air to the air cylinder 2'! through the air pipes 28 and 253 is regulated by a four-way control valve 3-5. With the valve in the position indicated in full lines in Fig. 1, a compressed air supply line 36 is connected through the valve to the lower air pipe 29 leading to beneath the piston in the cylinder 27, and the upper air pipe 28 is connected through the valve to an exhaust pipe 31 open to the atmosphere. With the valve in this position, therefore, the kick-off shoe and the upper coiling roller 18 are held in the position indicated in full lines in the drawing. By turning the valve handle 38 through to the position indicated in dotted lines, the connections through the air pipes 28 and 29 are reversed, as a result of which the upper coiling roll it is released to discontinue the coiling action of the coiling apparatus, and the kick-01f shoe is moved to eject (a the coil from the apparatus to the conveyor 3 The valve 35 is solenoid operated, and, in accordance with the invention, the operation of the valve solenoid is governed by an electrical control circuit including a timer which causes the coiling action of the coiling apparatus to be discontinued and the coil to be ejected by the kick-off shoe 22 at the proper moment after the trailing end of the sheet metal has emerged from between the rolls 13, so as to leave a tail of desired length on the coil. A control circuit for accomplishing this result is shown schematically in Fig. 2. The four major elements of this control circuit are a relay it actuated by emergence of the trailing end of the sheet or bar from between the rolls; a first timer 4!, the timing cycle of which determines the length of the tail formed on the coil; a second timer 42, the timing cycle of which controls resetting of the coiler kick-off mechanism; and the solenoid-operated valve.

The relay 29 shown in Fig. 2 is one that is actuated by the difference between the amount of electrical power supplied to the rolling mill motor l5 wh n the mill is operating under load with a bar of sheet metal passing therethrough, and the amount of power supplied to the mill motor when the mill is idling under nothing more than its friction load, with no bar passing there through. Specifically the relay comprises a solenoid i3 energized by a current transformer 34 inductively coupled with one of the conductors d5 of the three-phase power supply line to Which the mill motor i5 is connected. When energized, the solenoid 43 opens a switch 66 that normally is held closed by a spring ll. When the rolling mill is operating under a working load, and in consequence a relatively large amount of current is flowing through the conductors 45, the solenoid 43 is energized sufliciently by the current transformer 4 to open the switch 45. When, however, the rolling mill is idling under no load, the solenoid 43 is insufiiciently energized by the current transformer to hold the switch 46 open, and the switch therefore is closed by the spring 41.

The switch 46 is in series with a solenoid 48 in the first timer 4! and a power source 49 for the control circuit. When the switch 46 is closed, the solenoid 48 is energized, throwing the switch arm 50 of a single-pole double-throw switch into position to close with a first switch contact 5|. When the solenoid 48 is de-energized by opening the relay switch 46, the switch arm 5? is re" tracted by a spring 52 away from the first switch contact 5!, and into position to close with a second switch contact 53.

Motion of the switch arm 53 is controlled by a dash pot 5t, arranged so that retraction of the switch arm by the spring 52 to close with the second switch contact 53 occurs immediately upon de-energization of the solenoid 48; and so that movement of the switch arm 5!! in the opposite direction, upon energization of the solenoid 43, occurs only with some time delay. This is accomplished by a poppet valve '55 in the dash pot cylinder which opens to allow ready movement of the dash pot piston 5'3 in the direction urged by the spring 52, but which closes when the piston is urged to move in the opposite direction upon energization of the solenoid 423. A small air leak passage 5'! controlled by a needle valve 58 allows air to leak slowly into the dash pot cylinder when the energized solenoid 4B urges the piston in the direction in which the poppet valve closes, thus permitting the dash pot piston to move relatively slowly in the direction urged by the solenoid and to permit contact to be made between the switch arm 5% and the first switch contact 5! at the end of a time interval that is regulated by the setting of the needle valve 58.

The first switch contact 5| is in a series circuit with a relay a solenoid (ill in the second timer 42, and the control circuit power source it. Energization of the solenoid 6% occurs only when the switch arm 5c of the first timer is closed with the first switch contact 5!, and when the relay 59 also is closed. Closure of the relay 59 is effected by energization of a relay solenoid 6| in series with the powersource 49 and th second switch contact 53 of the first timer. closed mechanically, against the force of a relayopening spring 62, by engagement of the end (53 of the relay-operating arm with a catch 54 mounted on a switch lever arm 65 which the solehold 69 actuates. When the circuit through the first switch contact 5! of the first timer and the relay 5!! is completed, the solenoid 6B is energized, moving the switch lever arm 65 into position to close a pair of switch contacts 66. By this same motion, the latch 64 is disengaged from the end 63 of the relay arm, enabling the spring 62 to retract the relay arm and open the relay contacts, if the relay solenoid 6! is then de-energized. When the circuit through the solenoid (i is broken, either at the contact or through the relay 59, a spring 51 retracts the switch lever arm 55 to open the contact 68.

Movement of the switch lever arm 65 is regulated by a dash pot 68, arranged so that the lever arm 65 moves to close the contacts 66 immedi- It is held ately upon energization of the solenoid 60, but is retracted but slowly by the spring 67, after the solenoid becomes de-energized, so that opening of the contacts occurs only after some time delay. As in the case of the dash pot in the first timer, this is accomplished by means of a poppet valve 69 and a small air passage 'lll controlled by a needle valve ll. The poppet valve 69 is positioned to open and allow rapid movement of the lever arm 65. into position to close the switch contact but to close when the switch arm moves in the opposite direction. Movement of the arm 55 in the direction to open the contacts 65, therefore, occurs relatively slowly through a time interval governed. by the setting of the needle valve ll controlling the rate at which air can escape from the dash pot cylinder.

The switch contacts of the second timer 42 are in series with the power source 33 and a solenoid for operating the four-way air valve 35 controlling operation of the kick-oi? mechanism of the coiling apparatus 8 l.

The operation of the control circuit shown in Fig. 2 is substantially as follows: The contacts are all shown in the position they occupy just before introducing a bar (Or sheet) between the rolls l3 of the rolling mill Hi. In this position the relay switch 46 is closed, and the solenoid 48 of the first timer is thereby energized. Thus contact is made with the first switch contact 5! of the first timer, but the relay 59 is open, so that the solenoid ill of the second timer is not energized. Accordingly, the solenoid l2 controlling operation of the valve 35 is not energized, and the valve is held by a spring 13 in position so that the compressed air supply line 36 is connected with the lower pipe 25 leading to beneath the piston in the air cylinder 2?, while the upper pipe 28 is connected to the exhaust pipe 37. The coiling apparatus, then, is in position to receive and coil sheet metal issuing from between the rolls l3.

As soon as the bar or sheet enters the rolls i3, the increased power required by the mill motor results in a substantially increased current ilowing through the mill motor supply lines the. In consequence, the solenoid 43 of the relay is energized, opening the relay switch Thereupon the solenoid 48 of the first timer is deenergized, the circuit through the first switch contact 5! of the first timer is broken, and contact is made with the second switch contact This operation occurs without significant time delay. Thereby the circuit through the relay solenoid 6! in the second timer is completed, closing the relay 59, and this relay is held closed by engagement of the end 63 of the relay operating lever with the catch 64. The circuit through the second timer switch solenoid Bil, however, is still incomplete, notwithstanding closure of the relay 69, because now it is broken at the contact iii of the first timer. Consequently further happens as the bar continues through the rolling mill, until its trailing edge emerges from between the rolls. At this moment the power demand of the mill motor it: drops substantially, reducing the amount of current flowing through the mill motor supply line 35, and resulting in de-energization of the relay solenoid 5-3. Thereupon the relay switch 4t again closes, energizing the first solenoid 53, and moving the switch arm 50 into position again to close with the first switch contact 5|. As pointed out above, this movement occurs slowly, so that the closure with the first switch contact 5| occurs only after a time delay predetermined by the setting of the needle valve 58. At the end of this timing interval, a circuit is made through the contact and the now closed relay 59, energizing the solenoid es. Immediately the switch arm 65 of the second timer closes the contacts t6 and completes a circuit through the valve solenoid l2. Thereupon the four-way valve 35 is rotated 90, causing the coiling apparatus to discontinue its coiling action and resulting in ejection of the coil by the kickoii mechanism.

Movement of the switch arm 65 of the second timer to close the contacts 66 results also in releasing the end 63 of the relay lever arm, so that the relay is opened by the spring 62. In consequence, the circuit through the second timer solenoid til is broken again almost as soon as it is made. However, as pointed out above, the switch arm 55 is retracted but slowly by the spring 8?, so that there is a time delay determined by the setting of the needle valve ll before the contacts 58 are again opened and the valve solenoid i2 is again tie-energized. At the end of this time interval, the four-way valve is returned to its original osition by the spring 63, thereby resetting the coiling apparatus for receiving and coiling a new bar. When this has occurred the control circuit is again in the position shown in Fig. 2, and is again ready to begin the abovedescribed cycle of operations.

It is evident from the foregoing that the timing interval of the first timer (regulated by the setting of the needle valve 58) controls the length of the tail on the coil formed in the coiling apparatus. This it does, of course, by regulating the time interval that passes, following emergence of the trailing end of the bar from between the rolls of the rolling mill, before the coiling action of the coiling apparatus is discontinued and the coil ejected. For any given speed of travel of the bar through the rolling mill, an increase in this timing interval results in decreasing the length of the tail on the coil, and vice versa the tail length is increased by a decrease of this timing interval.

The timing interval of the second timer determines the period between actuation of the coiling apparatus kick-off mechanism and return of the kick-off mechanism to position for receiving a new coil. The timing interval of this timer therefore is not so critical as that of the first timer 4!; but it should be amply long enough to allow for complete ejection of the coil.

The particular type of relay ill shown in Fig. 2, which operates in response to the change in mill motor power demand that occurs between working-load and no-load operation of the rolling mill, is not the only type of switch means that may be employed. Still other forms are shown in dotted lines in Fig. 1. One alternative, for example, is a normally closed switch Hi mounted on the side of the rolling mill from which the rolled metal emerges, and in position to be held open by the car passing through the rolls. Such a switch will he opened directly after a bar is fed into the rolls i3, and will again close directly upon emergence of the trailing end of the bar from between the rolls, just as does the switch as of the relay 4!).

Still another switch means that may be substituted for the relay it is a normally opened switch it mounted on the rolling mill frame l2, and held closed by a rod 56 fastened at one end ii to the rolling mill frame at a point remote from the switch itself. Whenever a bar to be rolled is introduced between the rolls it, the strain imposed on the rolling mill frame causes it toexpand slightly, and this expansion is generally sufficient to produce enough relative movement between the switch '15 and the actuating rod 16 to allow the switch to open. of course, the switch in such case should be of the type designed for operation by very small mechanical movements of the order of a few thousandths of an inch. Such switches, however, are well known and readily available. The operating rod 15 shown in the drawings may be guided in its movement relative to the switch by a bearing eye [8. If the expansion of the rolling mill frame is not by itself suificient to produce the degree of motion of the rod l6 relative to the switch iii required to operate the latter, a motion-multiplying lever system may be substituted for the rod 16.

As shown in Fig. 3, when a coil '59 is ejected from the coiling apparatus ll, its tail to is at the bottom of the coil, and it is in this position that it is carried from the coiling apparatus on the conveyor 3 Frequently it is desirable to turn the coil over to bring its tail to the top, for convenience in presenting it to a subsequent rolling or other operation. For this purpose, a coil positioner 8! is included in the conveyor. The coil positioner consists simply of an angular cradle pivotally mounted on a shaft 82. The cradle is normally in the position shown in solid lines in Fig. 3, with one side thereof 83 forming an extension of the conveyor 35, and the other side 8 extending upwardly as a stop. An air cylinder 85 is provided. for moving the cradle through about its pivot shaft 82, to the position indicated by broken lines in Fig. 3. When so moved, the side 33 of the cradle that was previously in line with the conveyor 3G is brought to an upright position, and the other side 85 is brought into alignment with an extension 86 of the conveyor. Thereby the coil 39a is turned over, its tail tea being brought to the top, and in this new position it continues along the conveyor extension at. The air cylinder 85, by which the cradle is moved, is controlled by a four-way solenoid operated valve 8?, in substantially the same manner as the air cylinder Zl' of the ceiling apparatus is controlled by its four-way valve 35.

In accordance with the invention, a duplicate of the control circuit shown in Fig. 2 is employed to operate the cradle cylinder control valve 3'5, just as it is used to control operation of the coiling apparatus kick-off mechanism. In this case, a normally closed switch S8 is mounted in posi tion to be opened by a lever 39 promptly upon actuation of the coiling apparatus hick-off mechanism. The switch 85 here takes the place of therelay 4% shown in Fig. 2, and it is connected to the solenoid d8 of the first timer shown in Fig, 2. Otherwise the control circuit of Fig. 2 is just as described above, and its operation is of course the same, the only difierence being that the valve controlled thereby is the cradle valve 8? rather than the coiling apparatus valve 35. With this arrangement, actuation of the coiling apparatus kick oif mechanism opens the switch 88, de-energizing the relay #3 of the first timer so that its switch arm 56 is thrown into position to close the circuit through the relay solenoid El of the second timer 42. Then when the coiler kick-oil mechanism returns to its original position, again permitting the switch E3 to close, the switch arm 5i? of the first timer, after a time delay, returns to the position in which a circuit is completed through the first switch contact 5!, the relay 59, and the second timer solenoid til. This results in closing the contacts 65, actuating the solenoid control valve 81 to move the coil positioner cradle 8| through 90. After a time delay determined by the second timer 42, the cradle is returned to its original position, ready to receive the next coil ejected from the coilin apparatus. At this point the timing circuit is again in position to resume the above-described cycle of operations. The timing interval of the first timer 41 is, for this purpose, made suiiicient to allow the coil ejected from the coiling apparatus to travel down the conveyor to the coil positioner. The timing interval of the second timer 42 is made sufficient to allow the coil 13a to move oiT the coil positioner, before the latter is returned to its normal position.

Thus, in accordance with the complete invention, using automatic timer circuits for both forming a tail on the coil and reversing the position of the coil, this sequence of operations may be performed entirely automatically, resulting in a coil with a tail of suitable length and in position for introduction into the next operation to which it is to be subjected.

The control circuit has been described above in connection with Fig. 2 as involving the use of dash pots to achieve the desired timing intervals, and with needle valves to control the length of these time intervals. This has been done for the sake of clarity and ease of understanding the invention, but it is not necessary that dash-pot timers be used. As a matter of fact, commercially available electronic timer equipment is for many purposes superior to and more suitable than mechanical dash-pot timers. The invention, for example, has been employed successfully using the Model 520 electronic timer made by the United Cinephone Corporation, of Torrington, Connecticut, which timer has a timing interval adjustable in the range from 0.05 to 0.5 secend, as the first timer 4|; and using a Model 5413 electronic timer, made by the same concern, having a timing interval adjustable in the range from 0.1 to seconds, as the second timer 42.

It is equally possible to employ a vacuum-tube electronic relay in lieu of the solenoid actuated relay 4i! described above; and in fact in the installation using the electronic timers of the United Cinephone Corporation, such a vacuumtube relay was employed rather than a solenoidoperated relay.

The invention has been described above with reference to a particular form of coiling apparatus ll known in the art as a coiler. Another form of ceiling apparatus also used extensively in rolling sheet metal is known as a blocker. In their mechanical structures, these two types of devices are quite different, and they are used in somewhat different types of rolling operations. They have in common, however, that they are both designed to wind metal emerging from the rolling mill in the form of a coil, and they include kick-off mechanism for ejecting the coil after the bar has passed through the rolls. Accordingly, the invention contemplates, in lieu of the coiler shown in Fig. 1, apparatus in which a blocker is substituted as the coiling apparatus; and as used herein the term coiling apparatus is generic to both coilers and blockers.

I claim:

1. The combination with a rolling mill, with coiling apparatus for coiling sheet metal passing through said mill as it emerges therefrom, and with electrical means for deactuating said coiling apparatus, of means for automatically pulling a tail on the sheet metal coil including a source of electric power, a normally closed switch, means holding said switch open only when metal is passing through the mill, whereby said switch closes upon emergence of the trailing end of the metal from between the rolls, a time delay relay connected through said switch to said power source, whereby said relay is set in operation to begin its timing cycle upon closure of said switch, said time delay relay having contacts which close upon expiration of its timing cycle, said contacts being connected in circuit with said power source and with the deactuating means for said coiling apparatus, whereby upon closure of said relay contacts the coiling action of said coiling apparatus is discontinued and a tail of length determined by the speed of travel of the sheet metal through the rolls and the length of the timing cycle of said time delay relay is produced autonatically on the coil of metal formed by the coiling apparatus.

2. Apparatus according to claim 1, in which the rolling mill is driven by an electric motor, and in which the normally closed switch by which the time delay relay is actuated comprises a relay having contacts spring biased to a closed position and having an actuating coil connected to the mill motor power supply, said spring bias being sufiiciently strong to hold the contacts closed when the mill motor is operating under merely a friction load but being insufiiciently strong to hold the contacts closed when the motor is operating under a working load.

3. Apparatus according to claim 1, including means for varying the timing cycle of said time delay relay, whereby the length or" tail formed on the coil of sheet metal may be varied independently or" the speed with which the sheet metal passes through the rolling mill.

4. In apparatus comprising a rolling mill, coiling apparatus for coiling sheet metal as it emerges from said mill, a pneumatic kick-off mechanism for discontinuing the coiling action of said coiling apparatus, and a solenoid-operated valve for actuating said kick-off mechanism, the improvement comprising a switch, means for closing said switch promptly upon emergence of the trailing edge of the sheet metal from the rolling mill, a power source, a first time delay relay connected in circuit with said switch and said power source, whereby said relay is energized upon closure of said switch, said first time delay relay having contacts which close after said relay has been energized for the period of its timing cycle and which open promptly upon de-energization thereof, a second time delay relay connected through the contacts of said first time delay relay to said power source, whereby said second time delay relay becomes energized upon closure of said first relay contacts, said second time delay relay having contacts which close promptly upon energization thereof and which open upon completion of its timing cycle iollor ing de-energization thereof, the contacts of said second time delay relay being connected in circuit with said valve solenoid and with the power source, whereby said kick-off mechanism is actuated at the conclusion of the timing cycle of said first time delay relay and then is reactuated at a later time determined by the timing cycle of said second relay.

5. Apparatus according to claim 1 in which the normally closed switch is mounted on the rolling mill frame and which includes a switch operating rod, one end of said rod being mounted in position to operate the switch and the other end being connected to the rolling mill frame at a point sufliciently remote from the switch so that movement of the rod relative to the switch suificient to throw the switch occurs upon expansion and contraction of the rolling millframe incident to entrance into and emergence from the rolls, respectively, of the sheet being rolled.

6. Apparatus according to claim 1 in which the normally closed switch is positioned in the path of the metal sheet as it leaves the rolling mill and is there arranged to be held open by sheet metal passing through the mill.

HOWARD F. ANDERSON.

References Cited in the file of this patent UNITED STATES PATENTS Number Re. 19,590 537,437 1,779,115 1,837,209 1,871,665 2,060,672 2,289,986

Name Date Coe May 28, 1935 Buisson -1- Apr. 16,1895 Dallas e 1 Oct. 21', 1930 Dallas Dec. 22, 1931 Dallas Aug. 16,- 1932 I-Ieymann Nov. 10, 1936 Nelson July 14, 1942 

